Ventilated cushion structure



I March 12, 1968 HECKETHORN 3,372,406

VENT ILATED CUSHION STRUCTURE Filed Aug. 5, 1965 3 Sheets-Sheet l INVENTOR, Jomv 5 /EcKErHo/av BY M4 aywl fwd/m ATTORNEYS March 12, 1968 J. E. HECKETHORN 3,372,406

VENTILATED CUSHION STRUCTURE Filed Aug. 5, 1965 3 Sheets-Sheet 3 INVENTOR' Jay/vi. fi fc/a-mozzv ZMJQM, v

ATTORNEYS United States Patent Ofifice 7 Claims. (Cl. -347) ABSTRACT OF THE DISCLOSURE The seat spring pad or insert constituting the subject of the present invention comprises a circumferential frame of preferably rectangular configuration, made of wire of a suitably heavy gauge and of rounded cross section, together with an areal mesh fabric composed of intermeshed coils of wire of lesser gauge. The convolutions of the individual coils present, when viewed longitudinally of the coil, a substantially rectangular aspect, with the upper and lower horizontal reaches disposed approximately in flat almost uninterrupted contact with the inward surfaces of the covering fabric employed. The vertical reaches are in fact almost truly vertical so far as the longitudinal aspect of the coils is concerned and stand only at a quite limited angle to the adjacent vertical reaches of the interlocked adjoining coil. The crossed end portions of the individual wires of adjacent coils are twisted together a number of full turns to provide a tightly twisted double strand, with no flared ends, and the number of turns being adequate to provide sufiicient length of the terminal strand to surround the major portion of the adjacent cross section of the large gauge frame wire, preferably with the blunt end of the strand abutting the root portion thereof. Certain novel treatment of the coil ends results in a metallic hook structure to provide a close, strong permanent bonding encirclement of the frame wire. To provide a certain degree of relative vertical movement between the coils in use in order to enhance the comfort of the cushion, the vertical reaches of the coil configurations are of substantial height, being many times greater than the diameter of the individual wires concerned, and not mere looped or radiused intersections as in the case of conventional fence or partition structures.

This application is a continuation-in-part of my copending application Ser. No. 391,961, filed Aug. 25, 1964, now abandoned.

The invention disclosed and claimed herein relates to improvements in ventilated seat cushion structures of the general type exemplified in my United States Patent No. 3,103,671 of Sept. 17, 1963.

More particularly the invention relates to improvements in the spring pad constituting the internal structure of such a ventilated cushion.

In ventilated cushions of the type here involved, the spring pad, consisting of convoluted wire assembled within a substantially rigid marginal frame, is housed within a porous air-permeable cover or envelope to provide an air space permitting comparatively free circulation of air between the body of a user and the supporting seat struchire on or against which the cushion rests. As is wellknown, the wire coils, in addition to engaging and supporting the body of the user to provide an air space therebeneath, act as heat exchangers between the users body and the circulating air within or passing through the air space.

In many of the prior seat cushion pad structures it has been customary to bend or hook free ends of the wires forming the coils of the inner structure around a stiff 3,372,406 Patented Mar. 12, 1968 marginal wire frame in completing the construction. However, the strength and set of these end portions has been found to be insufficient to prevent them from unhooking or becoming loosened, thereby detracting seriously from the strength of the connection, the stability of the shape of the structure, and the insurance that the partially unwound and loosened ends do not form barbs which would endanger the surrounding fabric envelope of the cushion, the seat of the car, or the body of the user.

It is therefore one of the primary objects of the invention to eliminate such difficulties by the provision of a novel and improved pad structure. Those diificulties, and the need for much tedious hand work in the assembling process, have been obviated by the improved coil end and frame wire connections disclosed herein.

These improvements include the provision of a proper kind of low or medium carbon hard-drawn steel wire and processing it (either before or during the assembling thereof) to give it the required strength to prevent unwinding or loosening; intertwisting properly the individual wires of adjacent coils; accurately and precisely severing the resulting twisted ends so that they will be substantially co-terminous and free of barbs or sharp projections; providing a structure which can be manufactured for the most part mechanically, dispensing with some of the hand labor previously required; providing increased crush resistance as compared with prior pads while at the same time permitting relative vertical sliding movement between certain of the coil convolutions to better conform to the contacting surfaces in use.

Thus, the novel cushion in its entirety, possesses improved comfort and durability and the efiiciency of the inner spring pads as a heat exchange unit between the users body and the atmosphere is enhanced. And all this with a minimum expenditure of wire.

More particularly, the invention covers the novel pad the manufacture of which involves a choice of ways to render the intertwisted coil ends sufficiently strong to permanently maintain their firm hooked relationship with the stiff wire frame, and this involves ways to prevent the embrittlement of these wire ends. One process comprises annealing a relatively hard wire to render it easier to twist without embrittlement or crystallizing, the temper and hardness being restored by the twisting operation so that when the twisted ends are bent around the frame wire the hooks thus formed will take a permanent set, and have suflicient rigidity to strongly retain their shape so as to resist disconnection or loosening from the frame. However, I have also discovered that the annealing step may be dispensed within a preferred construction which involves the use of the hard drawn low or medium carbon steel, the twisting being accomplished in a peculiar novel progressive fashion to obviate the expected deleterious embrittlement.

As will be apparent, the heat exchanging efficiency of such a spring pad will depend in part on the area of its heat exchanging surface in close proximity to the body of the user and on the freedom with which air circulation is permitted through the spring pad.

In the device of my prior Patent 3,103,671, it was proposed to flatten the coil springs to an approximately oval configuration, but it has been found that such flattening of the springs has the effect of partially crushing them in such a way as to decrease the radius of curvature of the laterally opposed sectors of the individual spring coils, while at the same time increasing the pitch angles of these sectors, thereby reducing their resistance to further crushing and also the flattening of the coils generates a resulted in so constricting the air passages within the pad as to substantially impair the air circulation.

In the case of the present invention, however, the spring coils are formed of as nearly rectangular configuration as is practical, having due regard to the permissible minimum radii to which the selected wire may be formed without annealing so that, in the resulting coils, each convolution of the spring is defined by comparatively long and approximately rectilinear parallel reaches extending in substantially continuous diagonal rows, avoiding any tendency to roll, to comfortably support the user, and thus dispose a proportionately greater length of the coil in heat conducting relationship with the body of the user. These rows diagonally cross the longitudinally and laterally disposed strands of the cover fabric to thus support same with a minimum of wear and without penetration between adjoining strands.

These reaches are interconnected at their ends by relatively spaced and substantially rectilinear connecting or supporting reaches extending predominately perpendicularly to the longer lateral reaches which they interconnect. In accordance with an important aspect of the invention, the short connecting reaches may be of minimum pitch or inclination, and yet the comparatively long lateral reaches may be widely spaced between adjoining convolutions of a given coil. This results in unusually high strength and crush resistance even with the resulting wider spacing between adjoining convolutions of a coil, and a substantial reduction in the total length of wire required. Also increased comfort to the user will result. Due to the predominately perpendicular disposition and rectilinear shape of the respective supporting reaches, they will obviously provide superior resistance to crushing of the spring pad as contrasted to the generally sharply or cylindrically curved corresponding portions of earlier spring coils employed for the same purpose. Furthermore, these connecting reaches of adjoining coils cross and engage each other midway of the thickness of the structure to thus more than double the strength at these points and brace each other against lateral deflection, thereby contributing materially to the crush resistance of the entire spring pad.

It should not be necessary to mention that the height of the connecting reaches must be many times greater than the diameter of the wire involved in the construction of the mesh. If it were otherwise, the resulting pad would be no more useful in a seat cushion structure than a section of the well-known relatively inflexible diamondmesh or chain-link fence with its fully linked and fully radiused intersections.

Thus, because of the parallelogram shape, in plan defined by opposing portions of interlocked coils, an important contribution is made to the ability of the spring pad to resist lateral deformation in the plane of the pad. It will be a parent that the interconnected parallelograms defined by adjoining horizontal spring reaches will interact. in such a way that a longitudinal force tending to compress or lengthen the pad will result in a tendency toward deformation of the parallelograms, and thus be transmitted transversely to and through the parallelogram formation to the frame, and be resisted both by the frame and the spring coils. Thus, the general shape of the frame is maintained against deformation.

The accompanying drawing and following detailed description are exemplary only, but will serve to disclose what is presently contemplated as the best modes known to me, of practicing the invention. This of course will involve details. which may be omitted or changed in ways which will be obvious to those skilled in the art, without departing from the invention.

. In the accompanying drawings:

FIGURE 1 is a view in perspective of a ventilated seat cushion embodying the principles of the present invention, portions of the covering material being broken away to reveal the interior wire pad structure;

FIGURE 2 is an enlarged fragmentary view in cross 4 section taken on line 2-2 of FIGURE 1; and showing certain marginal connecting features of the inner pad;

FIGURE 3 is a similar view but with the covering omitted and showing the manner of bending the twisted wire ends around the peripheral frame of the pad, the view being taken approximately on line 33 of FIGURE 4;

FIGURE 4 is a fragmented condensed plan view of the novel pad in its substantially completed form ready to be inserted into the covering structure of the seat cushion;

FIGURES 5, 6 and 7 are fragmentary transverse strips of the wire mesh structure showing successive stages of the cutting, twisting, trimming, and wrapping of the adjacent ends of the coils comprising the mesh structure; and leading up to the substantially completed pad structure of FIGURE 3;

FIGURES 8 and 9 are fragmentary views of a pair of twisted wire coil ends suggesting the procedure and effect of the novel graduated stress method of twlsting employed;

FIGURE 10 is a fragmentary sectional view through a single spring coil of the pad structure, as taken approximately on line 1010 of FIGURE 4, the broken rectangular outline suggesting the approximate cross-section of a blade or mandrel on which the coil was originally formed;

FIGURE 11 is a fragmentary sectional view taken on line 1111 of FIGURE 4 and showing the approximate relative angular positions of the shorter vertical reaches of the coil convolutions in an un-stressed pad;

FIGURE 12 is a similar view of the same cross-over junction as when uneven pressure is applied to areas of the pad in the use of the cushion, and taken approximately on line 1313 of FIGURE 4; and

FIGURE 13 is a fragmentary vertical sectional view illustrating the relative vertical displacement of adjacent coils under varying stress in use.

Referring now in detail to the accompanying drawings, in FIGURE 1 at 10 there is illustrated a complete ventilated cushion structure of the type such as commonly employed on the seats of automobiles, oifice chairs and the like, and including both a seat portion 11 adapted for positioning for instance on a chair seat or on the seat of an automobile, and a back portion 12 adapted to over lie the back or back rest portion of the seat. The two portions 11 and 12 are of similar construction comprising; spring wire pads or assemblies 15 enclosed within a porous envelope or cover suggested generally at 16. Referring to FIGURE 2 in conjunction with FIGURE 1, it will be apparent that such cover is defined by opposed upper and lower sections 16A and 16B of loosely woven air-permeable fabric of generally rectangular configuration disposed on opposite sides of the spring pads 15.

The marginal edges of these fabric layers 16 are sewed together and bound around their margins, as at 20. Preferably also a line or lines of stitching 22 interconnects the two fabric layers of covering 16 between the adjoining edges of the respective spring pads 15 and generally coincident with the fold line defined between the two such pads when operatively positioned as in FIGURE 1. Thus the pads are properly positioned and retained within the envelope 16 defined by the fabric layers all in accordance with conventional practice.

It will be readily apparent that structures in accordance with the invention may incorporate either a greater or lesser number of spring pads than here illustrated and that the specific structure of the cover or envelope 16 is inconsequential, it being of importance only that such envelope shall be sufiiciently air-permeable to permit the free entry and escape of air into and from the cushion for heat exchanging contact with the spring pads 15 and with the clothing of the occupant of the seat.

Each of the spring pads 15 comprises a generally rigid rectangular marginal frame 24 which is here shown as formed in conventional manner from a length of relatively heavy and stiff wire, the ends of which are brought into abutting relation and secured therein by a conventional connecting sleeve or ferrule 25 as in my earlier Patent 3,103,671. The mesh or webbing comprising the greater area of the pads comprises wire coils 28 which are of uniform length and width, preferably though not necessarily extending from front to rear of the seat cushion. The laterally adjacent convolutions of adjoining spring coils 28 are interlocked in known manner, as suggested in FIGURES 11, 12 and 13, while the coil convolutions at the lateral extremities of the coil spring assembly thus provided are looped around longitudinally opposed parallel reaches of the marginal frame 24 in a unique manner to be later described.

The extremities of the respective spring coils 28 are connected to each other in pairs, whereby to assist in maintaining the desired relationship and positioning of the several coils in the assembly thereof, and also are connected to the longitudinally opposed sections of the frame 24.

As has been mentioned earlier, it is desirable to interconnect or unite the extremities of adjoining spring coils and also to firmly connect these to the marginal frame 24, and the specific means for accomplishing these connections, as well as the particular shape of the individual coils and their specific relationships, constitute important features of the invention. The difiiculty of achieving this in a manner to provide firm permanent inter-connections of the coil extremities to each other and to the frame presented a formidable problem, as long recognized in the art, this due to the known difficulty of efiiciently, properly, and accurately positioning the coils and securely attaching the numerous individual coil ends in a manner to eliminate the tendency to become unhooked from the frame and to prevent the formation of projecting ends forming barbs likely to snag or tear the envelope or covering fabric, the seat itself, or the clothing or body of the user.

Now, it was recognized that the strength of a single wire of rather small diameter is quite limited, and a hooked end of such a wire would have very little holding power in forming a connection with the frame. It is for this reason I provide pairs of intertwisted coil ends for forming the hooked connections, and this involves certain problems in relation to both rendering the wire ends sufiiciently pliable or malleable for intertwining or intertwisting, and also giving the twisted ends sutficient strength, rigidity, and holding power to make a permanent connection when bent around the frame wire, and without embrittlement. Certain solutions of these problems provided by the present invention will be described in detail following reference to the structural features of the product as shown more particularly in FIGURES 4 to 7 inclusive.

First, it may be stated that the individual coils 28 are formed preferably by winding a wire of the desired properties around a rotating blade or mandrel of approxi mately rectangular cross section, as suggested by broken lines at 128 in FIGURE 10, and the resulting successive lengths of coiled wire, having the configuration shown in FIGURES 4 and 10, are threaded into the convolutions of the next preceding coil and thus the mesh or webbing of the pad is formed.

The conditions of winding on the mandrel, including the hardness of the wire stock, will result in a convolution shape somewhat like that shown in FIGURE 10, wherein the longer reaches 28' and the shorter reaches 28" are both bowed very slightly but not enough to nullify the description of the outline of the convolution as substantially rectangular, as opposed to the ovate configuration of many prior art coils.

Thus, it will be understood that a further important feature of the invention consists in the specific shape and arrangement of each of the spring coils to provide maximum contact area with respect to the user, and maximum resistance to crushing, while requiring but a minimum expenditure of wire for its construction.

Referring again particularly to FIGURES 2, 3 and 10 of the drawings, it will be noted that While each convolution of a spring coil 28 is of generally rectangular configuration or cross section, including the generally rectilinear side reaches 28 and end or vertical reaches 28", these reaches are interconnected to each other by bends defining the corners of the substantial rectangle and which are as sharp as can practically be produced, having due regard to the limitations inherent in the wire from which the coils are formed. The general arrangement is therefore such that the ends or connecting reaches 28" extend generally rectinlinearly between the planes of the opposed side reaches 28' and are predominantly perpendicular to such planes. Furthermore, the connecting reaches 28 have small pitch angles. They are thus adapted to effectually resist the crushing force imposed upon them by the weight of the user and thereby to maintain within the cushion structure throughout its entire life an unobstructed or unimpeded air space permitting eflicient flow of air therethrough for heat exchange purposes.

On the other hand, the greater portion of the pitch angle of each convolution is comprised by its comparatively longer lateral or horizontal reaches 28. These reaches thus extend diagonally to the axes of the coils and are parallel, so as to extend as a series of parallel diagonal lines completely across the faces of the spring pad, and diagonally to the longitudinally and laterally disposed fabric strands of the porous cover. The possibility of penetration between strands of the cover is thus decreased, while comfort and durability of the cushion are increased accordingly. The coil configurations thus described are clearly shown in FIGURE 4 of the drawings as well as other figures.

It will be clearly understood thus that this interengaged coil mesh structure sufficiently approximates the truly rectangular concept so as to substantially achieve the benefits of great strength appurtenant thereto and yielding substantial improvements in crushing resistance over previous structures of this description. The very slightly arcuate reaches of the coils 28 provide improved seating comfort and coil position as compared to a completely accurate rectangular configuration. In previous so-called flattened coil structures, the coils with a circular cross-section are arcuately bent during the flattening process and therefore can offer no substantial compressive strength in resistance to crushing forces, and further bending of these already arcuately bent sections is likely.

By virtue of the present invention it will be further apparent that the generally rectilinear lateral reaches 28' of the respective convolu-tions adapted for supporting and heat conductive relationship with the body of the user represent a considerably larger proportion of the total coil length than is available in conventional rounded coil structures, thereby providing increased heat transfer qualities as well as improved comfort.

The interengagement of the coils 2 8 at the crossing points of the adjacent vertical reaches 28", as well as the substantially rectangular configuration provides a web or mesh constituting a pad insert for seat cushions in which the crush resistance is greatly enhanced. In fact, it has been found by actual test that the structure formed in accordance with the invention achieves a markedly greater crush resistance than is attainable in a conventional inner structure employing an equivalent amount of the same size and type of Wire. In tests run by a qualified testing laboratory, using hard-drawn wire of 0.038 inch in diameter, a crush resistance of 35.58 lbs. per square inch was obtained in a structure provided by the present invention, as compared to less than 16 lbs. per square inch using an equivalent amount of wire of the same size and type in a conventional parallel coil arrangement such as is employed in my prior Patent No.

7 3,103,671, and as disclosed in the Crane Patent No. 2,801,681.

Such tests also established that a substantially optimum included angle as indicated at a in FIGURE 11 of the drawings between the relatively crossed end reaches 28" of adjoining coils, is one which is somewhat less than say 30. This would mean an angle of approximately 15 with the vertical as indicated at b. With the connecting portions so inclined and with wire of the size and type above mentioned, a crush resistance in excess of 35 pounds per square inch was attained. As this angle was increased, this crush resistance dropped somewhat. For instance, the strength of the structure using the identical type of wire dropped to 30 pounds per square inch when the included angle a between the adjacent connecting reaches 28" was increased to 45. Widening the included angle beyond 50 rendered the resistance too low for satisfactory use.

The arrangement of coils in accordance with the invention, as shown in FIGURES 1 and 4, for instance, results in the provision of diagonally extending parallel rows of upper and lower or relatively spaced wire reaches 28', with the ends of adjoining reaches in each row in substantially overlapping relation and in such close proximity as to have the effect of a continuous diagonal rectilinear support. It will be noted that the strands of the fabric 10, as shown fragmentarily in FIGURE I, extend longitudinally and transversely respectively, whereas the rows of reaches 28' extend diagonally and thus contact the fabric 10 on a bias throughout the length of each row of diagonal reaches 28'. These very slightly curved reaches do not tend to project between the joining fabirc strands or cut through the strands as occurs in conventional parallel coil structures. This results in greater durability and greater comfort to the user than were heretofore obtainable.

Further, skewing or diagonal deflection of the frame 24 is strongly resisted in the provisions of the mesh pad structure described and the lateral shape retaining characteristics of the structure are greatly improved.

On the other hand, as demonstrated in FIGURES 12 and 13 of the drawings the substantially rectilinear configuration of the reaches of the coils permits some freedom of relative vertical movement between the adjacent coils. Although the demonstration in FIGURE 13 might be slightly exaggerated as compared with these relative movements in ordinary use, it does indicate how coils 28a, 28b, 28c and 28d may readily slide in vertical directions relatively to each ther under certain conditions of use, and thus accommodate the cushion to irregularities of the seat of shifting movements of the user.

Now it will be well to describe certain of the important novel features of the invention, namely, the trimming f the ends of the coils of the pad and the interconnecting of pairs of twisted ends with the frame 24.

It has already been explained that the respective coils 28 are formed on a mandrel as suggested in FIGURE 10 and immediately moved off the end of the mandrel in threaded interconnected relationship with the last previously formed coil of the mesh being constructed, while of course upon the completion of each pair of coils 28 the mesh is moved forward the width of two coils in the machine. This stage of the construction is clearly shown in FIGURE of the drawings where each successive coil has been threaded to the preceding one; and it will be clearly seen from this figure how, when the end of each coil as it comes from the mandrel is severed, a protruding length of wire 30 is left projecting from each margin of the Web of mesh constituting the area of the pad. It will also be seen from this figure that the pairs of crossed flared projecting wire ends 30 are indicated by the brackets as shown, and it is these paired ends 30 which are intertwisted to provide the hooked ends which are interlocked with the frame 24.

In the embodiment of the invention in which the annealing process is employed, these end projections 30 are subjected to a heating and annealing step intended to render them sufliciently pliable or malleable for easy intertwining or intertwisting. This annealing may be carried out through induction heating or in any other convenient manner. While it would be thought that the annealed ends would not retain sufficient strength and rigidity to permanently interlock with the frame member 24, it has been found that during the actual intertwisting and bending of the wires as shown at 35 in FIGURE 3 or suggested at 35 in FIGURE 7, there is produced a cold working of the metal which results in at least partially restoring the hardness within the twisted portions so that the resulting united or intertwisted end portions of the coils as at 35 may then be readily bent around the rod-like front and rear sections of the frame 24 to form rigid hooks, and to retain their gripping set.

However, a more preferred method of effectuating the interconnection of the ends 30 of the coils 28 does not require an annealing process and is also effectuated without embrittlement of the wire ends. The wire used is a low or medium carbon hard-drawn wire and the proper strength and rigidity for attaining a permanent interlock with the frame 24 is attained in the following manner.

From the condition shown in FIGURE 5 of the drawings, rotary twisting devices seize the diverging pair of projecting ends 30 of the adjacent coil 28 and by an appropriate camming or other variable driving mechanism the pitch of the screw of the receding twister progressively diminishes: first, a rather long pitch, then a shorter pitch, and a still shorter pitch which provides a gentle start of the twisting action and avoids crystallizing or overstressing the wire, but applies a delayed tightening action which ultimately results in a fairly uniform twist in which the wire is not overstressed nor embrittled but retains the proper hardness and strength to make an effective permanent joint with the frame 24. FIGURE 6 constitutes What might be called an instantaneous view f the twisting of the ends where the initial portion is somewhat loosely formed and of a rather long pitch as at 31. From this point on, the twisting element moving outwardly at a progressively decreasing rate causes the twist of the inward portion 31 to tighten up, at the same time the outward portions are being twisted. The final effect of the gradually diminishing outward movement of the twisting element causes the inner twisted convolutions as at 31 to be tightened up until the final twist of the paired coil ends 35 is taut and uniform as indicated at 33 in FIGURE 7.

Upon completion of the twisting in preparing the ends 35 for hooking over the frame 24, the projecting barbs 34 comprising the utimate ends of the wires 30 are snipped off, leaving a clean relatively smooth and uniform end structure 36 of accurately controlled length, for providing the precisely encircling hook-forming portion 35. This is clearly shown in FIGURE 7; and as a matter of fact, FIGURE 7 constitutes a plan view of the structure shown in vertical section in FIGURE 3 of the drawings with the twisted paired coil ends 35 underlying the relatively stifi' wire frame 24, preparatory to forming the hooks.

As a final step in the provision of the novel insert pads for the cushions, the intertwisted end portions 35 are bent upwardly around the preferably cylindrical frame wire structure 24 to substantially encircle the same as indicated at 40 in FIGURES 2, 3 and 4. The precisely cut free ends of the resulting hooks 40 are disposed within and very close to the frame structure 24 in near abutting relation with the adjoining section of one of the wire coils. This nearly complete encirclement of the frame wire 24 by the paired twisted wire end portions as at 40 provides complete security against unhooking; and by either method described herein, the strength of each of these connections is substantially in excess of any force tending to loosen 1t 1n service.

As indicated in FIGURE 3 of the drawings, the length of said twisted ends or hook-forming portions is such as would result from about four and one-half full turns of the wires; while in FIGURE 7, the twists results from approximately five or six turns. Thus it will be realized that both from the standpoint of adequate encirclement of the rim wire 24, and the firm interengagement of the wire end strands 30, any substantial reduction in the number of turns of the twist below that disclosed herein would result in a faulty and destructible cushion.

For the purpose of simplicity the orientation terminology in the claims will be referred to the condition of the seat portion of the cushion, although the claims also cover the corresponding features of the cushion back which is of course adapted to be disposed in a substantially upright position in use. Thus the words vertical, horizontal, up, down, lateral, etc. are to be considered to cover the features of the back member, as if the latter were laid out flat in a horizontal position.

It is understood that various changes or alterations may be made in the embodiments disclosed herein, without departing from the scope of the invention as defined by the following claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A spring-pad insert for .a seat cushion or the like, comprising a peripheral wire supporting frame and a wire mesh structure extending across the area bounded by said peripheral frame, said mesh structure comprising a series of successive substantially helical wire coils each interwoven with the next adjacent coil, successive pairs of adjacent coils having their end portions closely intertwisted and together providing a single hook engaging a portion of said peripheral frame adjacent thereto; said peripheral frame being substantially rectangular, the outside coils of the mesh structure looped around opposite side portions of said frame, and the series of intertwisted hooked coil ends engaging the other oppositely disposed side portions of the frame at intervals therealong; the extremities of said intertwisted hooked ends of the coils being disposed inside of and contiguously to said peripheral frame to eliminate any projecting barbs from the insert, in order to prevent possible snagging; the peripheral frame being formed of wire of substantially circular cross section, and the hooked coil ends snugly encircling side portions of the wire frame, and the extremities of the hooked ends abut the shank portions of said hooked ends adjacent the beginning of the convolutions of the coils.

2. A spring-pad insert for a seat cushion or the like, comprising a wire mesh structure consisting of a series of axially parallel wire coils, adjacent ones of said series being interlocked with each other; each of said coils being substantially rectangular in cross section as viewed in planes normal to its axis and having its opposite lateral reaches occupying spaced parallel planes defining the opposite faces of the pad structure; and connecting reaches extending through said pad structure from one of said planes to the other, the length of said connecting reaches being many times greater than the diameter of the Wire of which the mesh is formed, said lateral reaches being longer than said connecting reaches and having greater pitch angles than said connecting reaches.

3. A spring seat cushion structure comprising the pad insert as set forth in claim 2, in which said lateral reaches of the interlocked coils in each of said parallel planes are all substantially parallel with each other and arranged in groups to define practically parallel lines of nearly continous support within each of said planes due to the substantially rectangular configuration of the coils, together with a porous woven strand fabric envelope enclosing said insert, the strands of said fabric envelope being arranged in parallel relationship, the lines of substantially continuous wire support of the insert extending diagonally with respect to the axes of the coils and with respect to the strands of the envelope fabric.

4. A spring-pad insert for a seat cushion or the like, comprising a peripheral wire supporting frame and a wire mesh structure extending across the area bounded by said peripheral frame, said mesh structure comprising a series of successive substantially helical wire coils each interwoven With the next adjacent coil, successive pairs of adjacent coils having their end portions closely intertwisted throughout the length of such end portions and uniting to provide a single hook engaging a portion of said peripheral frame adjacent thereto; said peripheral frame being substantially rectangular, the outside coils of the mesh structure looped around opposite side portions of said frame, and the series of intertwisted hook-shaped coil ends engaging the other oppositely disposed side portions of the frame at intervals therealong; the extremities of said intertwisted hook-shaped ends of the coils being disposed inside of and contiguously to said peripheral frame to eliminate any projecting barbs from the insert, in order to prevent possible snagging; the peripheral frame being formed of wire of substantial gauge and of substantially circular cross section, and the hooked coil ends wound around and snugly gripping side portions of the wire frame.

5. The insert as set forth in claim 4 in which the wire coils are of ferrous metal and, in the final assembled form of the pad, the intertwisted hooked end portions are of sufficient temper, strength, rigidity, holding power, and freedom from embrittlement to maintain a tight grip on the frame, even after the twisting and hooking-bending operations.

6. The insert as set forth in claim 5 in which the coil metal is low to medium carbon, hard-drawn steel wire.

7. The insert as set forth in claim 4 in which each of the coils is of substantially rectangular cross-section as viewed in planes normal to its axis, and in which, in each substantially helical coil, the substantially horizontally extending reaches are of greater length and of greater pitch angle than those of the substantially vertical connecting reaches.

References Cited UNITED STATES PATENTS 482,337 9/ 1892 Campbell 2456 1,152,565 9/1915 Snedeker -107 2,300,718 11/1942 Williams et a1. 140107 3,058,125 10/1962 Zerbes 5-347 3,051,966 9/ 1962 Ness 5---347 3,103,671 9/ 1963 Heckethorn 5-347 2,954,076 9/ 1960 Crane et al. 5-347 XR 1,248,425 11/ 1917 McCallip 140-107 FOREIGN PATENTS 167,737 5/ 1956 Australia.

427,154- 5/1911 France.

585,873 10/1933 Germany.

BOBBY R. GAY, Primary Examiner.

DAVID J. WILLIAMOWSKY, FRANCIS K. ZUGAL,

Examiners.

ANDREW CALVERT, Assistant Examiner. 

